How thoroughly it is ingrained in mathematical science that every real advance goes hand in hand with the invention of sharper tools and simpler methods which, at the same time, assist in understanding earlier theories and in casting aside some more complicated developments. – David Hilbert

Mathematical science is in my opinion an indivisible whole, an organism whose vitality is conditioned upon the connection of its parts. – David Hilbert

The further a mathematical theory is developed, the more harmoniously and uniformly does its construction proceed, and unsuspected relations are disclosed between hitherto separated branches of the science. – David Hilbert